Select xml with namespace

Hello I was used to write SQL to extract data from record containing xml , for exemple :
WITH XML AS
(SELECT xmltype(c.MyColumn_XML) AS OBJECT_VALUE,
myemployee
FROM myRecordwith_MyColumn_XML c
WHERE c.MyYear='2021'
AND (c.MyProvider ='MyProvider'))

select myemployee from XML

but with namespaces this sql doesn't retrieve data.
What is the solution ?